US 8,300,758 B2Granted

Adaptive filter using shifted reverse interpolation

AssigneeQuantum Corporation

InventorMarc Feller

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Abstract

In one embodiment, an apparatus comprises an adaptive filter, a timing recovery unit, and a reverse interpolation filter. The adaptive filter has adaptive filter coefficients that are adjusted based on a first error signal at a first sample rate and filters a first signal at the first sample rate to obtain a second signal at the first sample rate. The timing recovery unit interpolates the second signal at the first sample rate to obtain a third signal at a second sample rate; and estimates a partial response signal at the second sample rate corresponding to the third signal. The a reverse interpolation filter interpolates a second error signal at the first sample rate, which is a difference between the third signal and the partial response signal, to obtain the first error signal at the first sample rate for feeding back to the adaptive filter.

Claims18

Dependent claims

An apparatus comprising:

an adaptive filter having adaptive filter coefficients that are adjusted based on a first error signal at a first sample rate, wherein the adaptive filter is operable to filter a first signal at the first sample rate to obtain a second signal at the first sample rate;
a timing recovery unit coupled to the adaptive filter, wherein the timing recovery unit is operable to:
interpolate the second signal at the first sample rate to obtain a third signal at a second sample rate;
and
estimate a partial response signal at the second sample rate corresponding to the third signal;
and
a reverse interpolation filter coupled to the timing recovery unit, wherein the reverse interpolation filter is operable to interpolate a second error signal at the first sample rate, which is a difference between the third signal and the partial response signal, to obtain the first error signal at the first sample rate for feeding back to the adaptive filter, and the reverse interpolation filter comprises:
a control unit operable to provide a first control signal that controls each sample interval at the first sample rate during which the interpolation of the second error signal occurs and a second control signal that identifies a timing offset within each sample interval at the first sample rate at which the interpolation of the second error signal occurs;
and
a first interpolator operable to re-sample the second error signal at the first sample rate to obtain the first error signal at the first sample rate according to the first control signal and the second control signal.

7 more elements

A method, comprising:

filtering, by an adaptive filter having adaptive filter coefficients that are adjusted based on a first error signal at a first sample rate, a first signal at the first sample rate to obtain a second signal at the first sample rate;
interpolating, by a timing recovery unit, the second signal at the first sample rate to obtain a third signal at a second sample rate;
estimating, by the timing recovery unit, a partial response signal at the second sample rate corresponding to the third signal;
and
interpolating, by a reverse interpolation filter, a second error signal at the first sample rate, which is a difference between the third signal and the partial response signal, to obtain the first error signal at the first sample rate for feeding back to the adaptive filter, comprising:
providing, by a control unit of the reverse interpolation filter, a first control signal that controls each sample interval at the first sample rate during which the interpolation of the second error signal occurs and a second control signal that identifies a timing offset within each sample interval at the first sample rate at which the interpolation of the second error signal occurs;
and
re-sampling, by a first interpolator of the reverse interpolation filter, the second error signal at the first sample rate to obtain the first error signal at the first sample rate according to the first control signal and the second control signal.

5 more elements

Dependencies are inferred from the claim text.